Taking oral solid medical drug products such as usual tablets and capsules can be problematic for the elderly having a weakened ability to swallow. The same problem is presented also for children with a low swallowing ability. As a dosage form suited for the elderly and children, there is a recent demand for the development of orally disintegrating tablets that quickly dissolve or disintegrate in the mouth.
However, efforts to make a tablet quickly disintegrable in the mouth generally result in lowered tablet hardness. Low tablet hardness may cause tablet cracking, for example, during the manufacture or packaging process or during the distribution, or when taking the tablet out of a packaging container, with the result that the commodity values decrease. Satisfying both of the oral disintegrability and tablet hardness at the same time is indeed an important factor in orally disintegrating tablets.
As a rule, tablet disintegrability and hardness are contradictory, meaning that efforts to improve hardness may lower tablet disintegrability. Further, the disintegrability of common tablets, and the oral disintegrability of orally disintegrating tablets are similar but different concepts. A measure that successfully satisfies both of disintegrability and tablet hardness in common tablets cannot easily satisfy both of the oral disintegrability and tablet hardness of orally disintegrating tablets.
There have been attempts to satisfy both of the oral disintegrability and tablet hardness of orally disintegrating tablets, as described in, for example, Patent Documents 1 and 2. Patent Document 1 describes a method of compression molding a granule obtained by granulating a poorly moldable sugar with a readily moldable sugar. Patent Document 2 describes a tablet obtained by compression molding a granulated material obtained by binding a mixed powder of a principal agent, an easily wettable sugar, and a disintegrant with a binder that contains an easily wettable sugar.
Patent Document 3 describes that a certain type of acrylic polymer, that is USP/NF methacrylic acid copolymer C can significantly increase the tablet disintegration rate, and can produce a tablet having highly desirable pharmaceutical characteristics, particularly excellent cohesion.